Sowerby's beaked whale

Mesoplodon bidens
Other names: 
  • North Sea beaked whale
  • North Atlantic beaked whale
Maximum length: 
  • Male: 5.5m
  • Female: 5.1m
  • Calf: 2.4m
Maximum weight: 
  • Male: 1,300kg
  • Female: 1,300kg
  • Calf: Unknown
Diet: 
  • Squid
  • Small fish
Estimated population: 
Unknown
IUCN Listing: 
DD
CITES Appendix: 
II
CMS Appendix: 
Not Listed
Classification: 

Sowerby's beaked whale was the first of the beaked whales to be discovered. An individual was stranded in the Moray Firth in 1800, and described four years later by the watercolour artist John Sowerby. While it is not commonly seen in the wild, it is one of the most commonly stranded beaked whales.

Appearance: 

From stranded whales a physical description of Sowerby's beaked whales can be made. It has a long, slender beak resembling a dolphin's, and a low melon in front of the blowhole. A pair of teeth erupt midway along the beak in adult males. This feature is distinctive, but is difficult to use as a means of identification as the teeth are only visible at close range. It has a spindle-shaped body and is dark bluish-grey in colour, with a sandy colouration on the head and beak. The underside is lighter, especially in young animals, with grey or white spots. The flippers are long compared to other species in the beaked whale family. The dorsal fin is small and curved with a rounded tip. Their tail flukes are dark on both sides and as with other Mesoplodonts, there is no middle notch.

Behaviour: 

Little is known about this beaked whale's behaviour as they are rarely seen at sea. Sowerby's whales have been described as bringing their heads out of the water at a steep angle when surfacing. They have been seen in groups of up to ten individuals, and they have occasionally been seen tail-slapping, breaching and spy-hopping. Dives of between 12 and 28 minutes have been recorded with the whale resurfacing up to 800m away from where they last dived. When stranded they make a sound similar to that of a cow mooing.

Distribution: 

Sowerby's beaked whales have one of the most northerly distributions of all the beaked whales. They are found in the eastern North Atlantic, in the seas around Norway, the UK and Iceland, and in the western North Atlantic off of Canada and Massachusetts, USA. As with other species of beaked whales, Sowerby's beaked whales prefer deeper waters and are found offshore past the continental shelf. Threats to the species may include incidental whaling, accidental entanglement in fishing gear, climate change, marine debris, and noise pollution and whilst the worldwide population is unknown the IUCN list the species as Data Deficient.

Distribution map: